Date post: | 02-Jun-2018 |
Category: |
Documents |
Upload: | nindy-vika-r |
View: | 235 times |
Download: | 0 times |
of 21
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
1/21
OOGENESIS
By
Dr Samina Anjum
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
2/21
Female Reproductive System
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
3/21
PRIMORDIAL GERM CELLS
Gametes are derived
from PGCs.
Formed in the epiblast
during 2ndweek and
then move to the wall of
yolk sac, begin to
migrate from the yolk
sac in the 4thweek and
arrive in the gonads byend of 5thweek.
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
4/21
In preparation for fertilization germcells undergo:
Gametogenesis
Oogenesis
Spermatogenesis
Cytodifferentiation
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
5/21
OOGENESIS
Is the sequenceof events by
which germ cells
oogoniadifferentiate into
mature oocytes.
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
6/21
Maturation of oocytes begins before
birth.
Accelerates at puberty. Ends at menopause.
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
7/21
Morphological changes during
maturation of gametesMaturation of oocytes
begin before birth
End of 3rdmonth
Mitotic
division
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
8/21
egmen o ovary s ow ng
different stages of
developmentMajority of oogonia
continue to divide by mitosis
but some arrest their cell
division in prophase ofmeosis I and form primary
oocytes
By 5thmonth number of
germ cells reaches 7 million
in the ovaries.
Cell death (atresia) begins
By 7thmonth majority of
oogonia and primary oocyte
degenerate.
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
9/21
All surviving primary
oocytes have
entered the prophase
of meiosis I, and most
are individually
surrounded by flat
epithelial cellsto formprimordial follicle.
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
10/21
Maturation of oocytes
continue at puberty
At birth: The total number of primary oocytes atbirth is 600,000 800,000
All Primary oocytes are arrested in theDiplotene stage (resting stage during prophase,characterized by lacy network of chromatin) tillpuberty.
This arrested stage is due to OMI secreted byfollicular cells.
By puberty: Number drops to about 40,000 by thebeginning of puberty. Rising FSH triggers start ofovarian cycle
Ovarian cycle: Fewer than 500 ovulate in thereproductive life of a female
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
11/21
At puberty a pool of growing follicles is
maintained from primordial follicles
Each month 15-20 follicles begin to matureand pass through 3 stages:
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
12/21
Primary Follicle (Preantral stage)
Follicular cells will form astratified epithelium/granulosa
cells around the primary oocyte
Granulosa cells rest on abasement membrane that
separates them from ovarian
connective tissue (stromal
cells) that form theca folliculi.
Zona pellucida- a layer of
glycoprotein secreted by
granulosa cells and oocyte
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
13/21
Growing follicles
As the follicles continue to grow cells , cells
of theca folliculi organize into layers.
Finger like processes of follicular cells
interdigitates with microvilli of plasmamembrane of oocyte
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
14/21
Secondary/Antral/Vesicular Follicle
At maturity size reaches(25mm)
Longest stage
Stratum granulosum 6-12 cell
layers
Liquor folliculi (hyaluronic acid)
Formation of Antrum
Granulosa cells surrounding the
oocyte remains intact and oocyte
is off center.
Well defined Theca interna &
externa
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
15/21
Tertiary or Graafian Follicle
(Preovulatory stage lasts for 37 hrs)
Spans entire width of cortex &
produces a bulge on the
surface of ovary
St. granulosum appears to be
thinner One large antral cavity
Cumulus oophorus & corona
radiata (loose connection)
A surge in LH, First meiotic
division being completed:Primary oocyte divides into a
Secondary oocyte and a polar
body
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
16/21
Cumulus oophorus
Is a column/mound of
granulosa cells that
attaches the oocyte to thefollicle wall. At ovulation,
this column of cells is
broken or separates to
release the oocyte fromits follicle attachment.
Corona radiata
Is composed of
cumulus/granulosa cellsthat immediately surround
the oocyte & send
microvilli through ZP that
communicate with
microvilli of oocyte
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
17/21
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
18/21
Lies in perivitelline space
mitosis
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
19/21
Maternal Contributions to the
Oocyte
As the oocyte is a product of
female gametogenesis, the maternal contribution to
the oocyte and consequently the newly fertilized
egg is enormous. There are many types of
molecules that are maternally supplied to the
oocyte which will direct various activities within the
growing zygote.
Half of zygotic genome
Maternal Mitochondria
Maternal Nucleolus
Maternal Ribosomes
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
20/21
Paternal Contributions to the
Oocyte
Half of zygotic genome
Centriole
8/10/2019 presentasi Oogenesis (biologi SMA XII ipa)
21/21